A car expense tracker that lives inside your budget

If you want to know your car's fuel consumption, cost per kilometer and service history, you install a dedicated vehicle app — Fuelly, Drivvo, Fuelio, aCar. If you want to know where your salary went, you install a budgeting app — YNAB, Bluecoins, Spendee, MoneyWiz, PocketGuard. Neither family crosses into the other's territory.

So every tank of fuel gets typed twice: once as 52.4 liters at 1.71 €/l, odometer 184,203 km in the car app, and once as €89.60, category Transport in the budget app. Miss one and your fuel-economy chart is wrong. Miss the other and your monthly budget is wrong. Do it properly and you have done double-entry bookkeeping by hand, on your phone, at a gas station, in the rain.

FlexiBudget records the vehicle detail and the money in a single entry. The refuel shows up in the vehicle's fuel log and under Vehicle → Fuel in this month's budget, from one form. That category is bound to the refuel event type, which is the mechanism doing the work — not a convention you have to remember to follow.

Each refuel or charge captures:

• the date and the odometer reading (or hour meter, for machines measured in running hours);
• the amount taken on board — liters, gallons, kWh, m³ or kg, depending on the fuel type;
• the price per unit and the total paid, in any currency;
• the fuel type and product — 95 versus 98, winter diesel, home versus ultra-fast charging;
• which tank mark the stop hit — brimmed to full, or the low-fuel warning light — which is what makes tank-to-tank consumption math honest;
• the station or payee and the account or card it was paid from.

From those, the app derives fuel consumption between matching tank marks, average price paid per unit, distance covered per period, cost per kilometer and total spend per vehicle per month — and the same entry feeds your budget totals with no second step.

That second tank mark is worth dwelling on, because most fuel logs only offer the first. Measuring consumption needs two fill-ups at a known, repeatable fuel level, and brimming the tank isn't the only one available: the low-fuel warning light comes on at a fixed level too, somewhere around 10–15% remaining depending on the car. So FlexiBudget accepts either anchor and measures full-to-full or empty-to-empty, whichever you actually mark.

The two can't be mixed inside one measurement without knowing the tank's capacity, so a vehicle's history is read through one anchor at a time — and by default the app picks whichever you've marked more often, so you get the most segments out of the log you already kept. On an EV the same two marks read as charged to full and low battery warning.

A vehicle can hold several fuel types at once, and each refuel is recorded against a specific one. Supported types are gasoline, diesel, LPG/autogas, CNG/natural gas, electricity, AdBlue/DEF and hydrogen. Each carries its own unit, and most carry an optional product variant:

• Gasoline — 91, 95, 95 premium, 98, 98 premium, E10, E85
• Diesel — regular, premium, winter, arctic, biodiesel B7/B100, GTL, red diesel
• LPG — propane, butane, mix
• Electricity — home, work, slow, medium, fast, ultra-fast

That matters for the awkward cases. A plug-in hybrid keeps its gasoline and its kWh in separate averages, so neither pollutes the other. An LPG conversion — a gasoline car retrofitted with an autogas tank and injectors so it runs on either fuel — keeps LPG and gasoline consumption apart. That separation is the only way to answer the question that made you convert in the first place: LPG costs roughly half as much per liter but you burn more of it, so how many kilometers until the install pays for itself? A diesel with AdBlue tracks the DEF top-ups as their own line.

Fuel economy can be displayed as fuel per 100 distance (L/100km), fuel per distance (L/km) or distance per fuel (km/L, or miles per gallon). Distance is kilometers, miles or running hours, and the default form is inferred from that choice — set a vehicle to miles and its economy reads as MPG, set it to hours and you get a burn rate in L/h, which is how hour-metered machines are actually rated. You can override the default on the vehicle itself.

The setting is per fuel type, not per vehicle, which is what a plug-in hybrid needs: gasoline read as MPG, electricity read as kWh/100km, on the same car.

A service entry records what was done, with parts and labor split out, so you can see how much of the year's maintenance bill was components and how much was workshop time. Service intervals generate reminders by distance or by date — the mechanism that stops a timing belt or an inspection from arriving as a surprise.

The history stays attached to the vehicle for as long as you own it, which is also the document you want when you come to sell it.

The data model is deliberately generic — there is no "vehicle type" field, because a motorcycle, a work van, a delivery truck, an e-bike, an e-scooter or a boat all need exactly the same things: a meter reading, an amount of energy, a price, and a service history.

Machines measured in running hours rather than distance work too. The odometer becomes an hour meter, and costs report per hour instead of per kilometer — useful for a generator, a ride-on mower or a boat engine.

See how the budgeting half works in flexible budgeting, check which devices it runs on, read the FAQ, or compare against Fuelly, Drivvo and Fuelio.